<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        function Cat(){
        };
        var str = '1230';
        var num = 123;
        var boo = true;
        var arr = [];
        var obj = {};
        var fun = function (){};
        var cat1 = new Cat();
        console.log(str.__proto__);//String.prototype
        console.log(num.__proto__);//Number.prototype
        console.log(Function.prototype.__proto__);//Object.prototype

    </script>
</body>
</html>